judging by the fact that the Filling Station rubber diagrams are exact copies of the Steele illustrations, they are no doubt a Steele vendor .... and usually a bit cheaper

Steele insures vendors they [Steele] won't sell for less than suggested retail, but doesn't restrict vendors from better prices
my experience has been that if you ask, any vendor will tell you their source company - also in my experience, you want to avoid rubber from SofSeal
Bill